The Colorado Adoption Project assesses genetic and environmental influences as they interact in the development of behavior. During the fourth year of this study, a behavioral test battery will be administered to approximately 150 biological (unwed) parents, 140 adoptive parents, and 130 "control" parents (rearing their own children and matched to the adoptive parents). Behavioral assessments will be obtained for adopted and "control" children during approximately 390 home visits. The data bank for the adults includes background and medical infomation and data on the major factors of specific cognitive abilities an personality. For the children, the behavioral assessment uses standard objective tests of cognitive abilities, observational ratings, interview data, and time-sampled observations of their behavior. An important aspect of the project is its environmental assessment obtained from the time-sampled observations and from parental interviews using newly developed environmental assessment measures. This project will provide the first multivariate analysis of environmental and genetic influences in behavioral development using the powerful full-adoption design in a prospective and longitudinal study. It will also lay the foundation for studies of the later behavioral development of this unique sample of adopted nd "control" children.